Jessie Garcia suffered four concussions as a kid, and each one--incidents with a bowling ball and a few softballs--knocked her out. So when the then Lehigh University student took a hard hit in a rugby game and got right back up, it didn't dawn on her that she was concussed.

"I was seeing stars," says the now 28-year-old. "I was thinking, why am I making my eyes go crossed? I didn't even know that was a symptom to think about."

After her club sports coach reviewed the game's footage, she emailed Garcia to apologize for keeping her in the game when she had clearly taken a hard hit to the head.

"I had post-concussion symptoms for months," says Garcia. "I didn't know I should have gone to the doctor. I went out that night. I did everything wrong. If I had known, of course I would have listened to whatever protocol there was. But we didn't have that."

It was this injury, which has affected Garcia's ability to read the way she used to, that sparked an idea: a mechanical sensor that would turn red when it detected concussion-level impact.

"I've always been a really curious person," says Garcia, who graduated in 2012 with a degree in global studies and entrepreneurship and then with a master's from Lehigh University in 2013 in engineering and technical entrepreneurship.

"I've become really good at empathetically viewing problems and with my entrepreneurship education, I've learned how to monetize problems with a solution. But I felt this void: How do I make a solution for those problems?"

At first, Garcia wanted this concussion sensor to work in a mouth guard; she points out that not all contact sports--like rugby and ultimate Frisbee--require the use of helmets. But after conducting market research and talking to athletes and their coaches, it turns out many players don't wear their mouth guards, or if they have braces, wear one provided by their orthodontists.

"Our product is no good if you don't use it," she says. "If you're not wearing it--Steph Curry (of the Golden State Warriors basketball team) always has his hanging out of his mouth -- it defeats the purpose."

So Garcia returned to targeting helmeted sports.

In 2013, Garcia started developing a prototype for her now-named company, Tozuda, a nod to her grandmother who tells Garcia, "Tu eres muy tozuda," or, you're very hardheaded, in Spanish.

"That's not because of my head injuries but because I've always been really strong-willed and determined," she says. "I totally embraced it."

Tozuda produces a mechanical sensor that would turn red when it detected concussion-level impact. (Courtesy photo)

The sensor is a 1.25-inch-by-.25-inch plastic capsule that contains a spring, two steel balls, a clear liquid, and a red powder dye. Using an accelerometer and gyroscope, when a helmet sustains a certain amount of gravitational force (g), the red powder will release, turning the liquid red. This trigger point will vary based on the wearer's age and weight. For example, a 10-year-old who weighs 85 pounds will have a different trigger point than an 18-year-old linebacker who weighs 200 pounds, explains Garcia.

The trigger points are determined by data from the department of orthopedics at Brown University, which found that impacts of 75 g had a 50 percent chance of causing a concussion. To put that in perspective, a high school football game has an average of 30 g.

While there are electronic sensors available, Garcia pursued the mechanical mechanism for a few reasons. First, the cost: Electronic sensors are much more expensive, making them hard to come by, especially in lower-income areas.

"Coaches can't outfit an entire team with an electronic version," says Garcia. "And then the question becomes, who do we give the good helmets to? The idea is that everyone deserves to play safe. Every kid on the team should have a head impact awareness device, not just the people with money."

Cost aside, when a device relies on electronics, things can go wrong. For example, not being able to connect to WiFi or Bluetooth. Or, in one case Garcia came across: A football player was wearing a $1,200 Riddell helmet equipped with a sensor but continued to play after a cringe-worthy collision. He had forgotten to charge the helmet.

Garcia also points out that athletes who want as much playing time as possible can turn off their sensors so they can't be pulled from a game if they're hit too hard. The Tozuda model is tamper-proof, and once the red dye is released, the player will need a new one.

And at $29.99 a pop, Tozuda won't break the bank. It's also incredibly accurate, within 5 g.

Tozuda will outfit a small group of athletes this fall -- teams Garcia has worked with in her research stage. One of those groups is a youth football program in South Philly, the Sigma Sharks. Every player -- nearly 200, ages 5 to 14 -- was given the King-Devick concussion-screening test to measure baseline functions that can be used if a concussion is later suspected through the Tozuda sensor.

"Partnering with Jessie made sense based on what we're already trying to do: use technology to help coaches and prevent traumatic brain injuries," says Darron Carpenter, vice president of the Sigma Shark organization. "We're trying to become a model organization for youth football around the country in terms of safety."

Carpenter, whose own 11-year-old son plays football, understands why parents are worried about safety in the sport. But he says education among parents and coaches is the first step to making it safer. Tozuda can help with that.

"I can't say 100 percent that (the Tozuda sensor) will make football safer, but it's a great tool to help us coaches know when to look out. It will help the coaches save themselves from themselves. We get caught up in the moment. We're competitive. But the sensor is a no-miss way to know if a kid has to come out of the game immediately," he says.

The Tozuda model is tamper-proof, and once the red dye is released, the player will need a new one. (Courtesy photo)

But it's not just football players who will wear the sensors this fall. One notable backer of the Kickstarter campaign is an equestrian coach.

"I was having a conversation with this trainer and she said in the steeple-chasing event, the first thing she does if a girl gets bucked off is to tell her to get back on immediately so she doesn't get scared of the horse. The trainer said she felt horrible for putting them back in danger without even realizing it because she hadn't assessed them for a head injury," says Garcia.

Because of this customer, Garcia has collected data on horseback riding. "Now we know that when riding a horse, it's an average force of 5 to 10 g for normal up-and-down riding," she says.

After the initial product rollout, Garcia hopes to sell her sensor in stores and through online retailers like Amazon.

"I'm really excited to keep people active," she says. "I love sports so much, and some of the best memories I have are from sports teams I've played on. The last thing I want to do is scare people into not playing. Like with any injury, you just have to know when to address it."

And that's how her dad came up with the company's slogan: If it's red, check your head.